This invention relates to a mechanism for moving a stage on a planar or cylindrical surface.
Mechanisms for moving a stage on a planar surface are extensively employed in various fields, for example, a microfilm moving device in photographing or retrieving of microfilm, an integrated circuit inspecting device, or a drafting plotter. In these movement mechanisms, it is necessary to move the stages quickly with a short settling time and high accuracy. For instance, in a computer output microfilmer (COM) for providing the output of a computer in the form of microfilm, it is necessary to move a stage holding a film to predetermined positions at high speed with high accuracy to successively photograph the output of the computer.
In order to photograph the output of the computer immediately after the movement of the stage, it is necessary to quickly damp the vibration of the stage as soon as the stage is moved to the predetermined position. That is, the settling time which elapses from the instant that a drive source (such as an electric motor) for moving the stage is stopped until the vibration of the stage caused by the movement is stopped should be as short as possible. However, the settling time of a conventional movement mechanism is not sufficiently short, and accordingly, it is necessary to improve the movement mechanism to provide a satisfactory high-speed COM.
X-Y movement mechanisms for microfilm cameras have been disclosed in a number of specifications of Japanese Patents. Typical are publication No. 14266/1974, Japanese Patent Application Laid-Open Nos. 63722/1973 and 3816/1978, and Japanese Utility Model Laid-Open Nos. 6640/1978 and 6641/1978. In each of these conventional X-Y movement mechanisms, the stage is moved by one motor for moving it exclusively in the X-direction and a second motor for moving it exclusively in the Y-direction. In most of these conventional movement mechanism, one (Y-direction) movement mechanism is placed over the other (X-direction). Accordingly, the motor for moving the stage in the X-direction should output a greater torque. Furthermore, in order to transmit the power in the Y-direction, it is necessary to use spline means or to place the motor itself on a carriage. Thus, in these conventional movement mechanisms, it is necessary to use motors which can provide great torque, and use intricate mechanisms to transmit the power thereof. Accordingly, it is difficult to minimize the size of the movement mechanisms.